Comparison between the geometrical optics amplification and the wave optics amplification for an isolated point mass. We compare the geometrical optics approximation (full lines) with the wave optics magnification (dashed lines) for an isolated point lens of mass M_L = 100 M_⊙ at the origin of the image plane and source position β = (0, β₁) rad. The error on the geometrical optics approximation rapidly reduces for frequencies f ≳ 100 Hz and systems with higher source displacements.